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RE: Variacs, HV Jell, and LTRS Caps
Hi Terry:
I repotted my NST in melted Vaseline jelly. It was easy, just melted it
in a pot (to a water-like viscosity) and poured it in, and it re-jelled
to its original consistency. It's given me no problems, breakdown or
leaking-wise, since.
What is the thinking behind the potting of your caps? I would have
thought that something internal to the cap would break down before you
got arcing externally?
Regards, Gary Lau
Waltham, MA USA
>Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>
> Also, I am working on a new MMC cap design that will require that
>they be submersed in oil. I am running them above their ratings (in the
>"enhanced" mode :-)) taking advantage of the fact that "I know things"
>:-)) Since oil is such a mess, I was wondering if mixing mineral oil and
>say paraffin would produce a jell that could be heated to flow but would
>solidify like grease when cooler? The jell would not be a dielectric but
>more of an insulator and mounting medium to put the caps in nice PVC
>cases. The advantage would be it would not run, spill, leak, etc. If
>this works, I can make a 5.6nF cap for about $25!! If it doesn't, I
>don't want to have to clean up a bunch of oil :-)) This will test if the
>manufactures ratings really do mean anything in Tesla coil applications.
>I am running just over the edge in voltage and current but theoretically
>they should hold up very well. My present MMC runs soooooo cool I think
>it may be a waste of money to over design these things too much. More
>exploration of their limits is called for. Since I have all my stuff
>modeled, I can predict RMS currents and voltages very well so as to push
>the rating of the parts "gently"...
>
> I have been running a small coil off a 27nF
>(larger-than-resonant-sized (LTRS)) cap with a 15kV/60mA transformer the
>last few days. All seems to be working as expected and the output seems
>much better than my old 17nF configuration. Much more to learn about
>this. I think this is a very promising area despite the theoretical
>complexities. Much more to come about this...
>
>Any thoughts are welcome...
>
> Terry